1. Field of the Invention
The present invention is directed to a fastener for use in applications where installation into a material may result in a shaving or shavings of the material being created. In particular, the present invention may be particularly well-suited to installation in steel or steel mounted on wood.
2. Description of the Related Art
Fasteners are routinely used to install metal panels, such as roofing panels, or to secure metal panels to wooden backings or supports. In addition, a washer such as a rubber waterproofing washer may be installed between the metal and the underside of the fastener head.
During the installation process, one or more shavings of material may be formed from the hole in the panel made by the fastener. These shavings may work their way outward and have multiple detrimental effects. For example, the shaving may abrade the panel or may enlarge the hole beyond the minimum amount necessary, removing rust barriers such as the paint that may be on the panel, which may contribute to premature corrosion of the panel. In addition, the shaving may either cut or otherwise damage the washer, or it may inhibit the washer from mounting flushly between the panel and the underside of the fastener head. In either case, this may create a leak path underneath the washer, which, in the example of a fastener located on a roofing structure, may lead to roof leaks and premature deterioration of the structure.
To alleviate this problem, in the past, an installer would expend extra labor by attempt to manually remove as many shavings as possible and/or by pre-punching holes in the panels. In addition to being time consuming, this process was limited by the fact that the installer likely would not be able to remove the entirety of each shaving since at least a portion of the shaving would have been compressed between the fastener and the substrate. As one indication of the widespread nature of this issue, during testing, a traditional gimlet-pointed fastener such as the type shown in FIG. 2 may have created shavings approximately 73% of the time during testing on 26 gauge steel panels.
Several attempts have been made to minimize the production of shavings. As seen in FIGS. 3-5, these attempts include removing portions of the fastener near the tip. For example, one proposed solution was to use a “type 17 point” fastener having a flute near the tip that consists of two sides, one side extending axially, each side extending radially and at about a 90 degree angle to one another, as seen in FIG. 3. This design slightly reduced the prevalence of shavings being formed, but only to the frequency of about 50%.
Another attempt to minimize the presence of shavings includes using a fastener having a rightwardly angled flute, such as the one shown in FIG. 4. This structure, however, is even less favorable than the gimlet-pointed fastener of FIG. 2, actually resulting in more shavings being formed, i.e., about 78% of the time during testing.
In an additional variation, an “X-point” tip, such as the one shown in FIG. 5 has been used. This X-point tip may be formed by axially offsetting two halves of a generally conical drilling tip. This arrangement results in fewer shavings being produced as compared to a traditional gimlet-pointed fastener. However, it still produces shavings about 20% of the time.
What is needed is a fastener that can be used to install materials such as steel roofing panels or steel panels mounted on wooden substrates and that reduces or minimizes the frequency of shavings being formed.